This invention relates to spring units for use in sprung units such as, for example, beds, divan beds, mattresses, upholstered items and the like, and the invention is more particularly concerned with pocketted spring units for use in such articles.
A pocketted spring unit generally consists of a pocket of fabric or other suitable material in which is located a spring, the ends of the pocket being closed so as to retain the spring within the pocket. Such a pocketted spring unit comprises a single pocket and a single spring within said pocket, a plurality of such pocketted spring units being used in the formation of a sprung unit such as is referred to above.
In publication No WO 98/25503 there is disclosed a composite spring unit for incorporation into a bed, divan bed, mattress or other upholstered unit, the composite spring comprising a first pocket containing a spring and a second pocket containing a spring, the second pocket being wholly within the first pocket and being such that the second pocket and its spring is freely movable within and relative to the first pocket.
In U.S. Pat. No. 3,462,779 there is disclosed a cushion comprising two spring layers which are separated by a resilient layer of deformable material, each spring layer consisting of a plurality of what may be termed xe2x80x98spring unitsxe2x80x99. Each of the xe2x80x98spring unitsxe2x80x99 includes a plurality of coil springs which are positioned in a side-by-side relationship, the coil springs being located between discrete segments of spring covering material, the segments being seamed together along the edges of the material and laterally of the material so as to isolate the springs within the material one from the other. In each of the xe2x80x98spring unitsxe2x80x99, the springs are located side-by-side such that the springs of each xe2x80x98spring unitxe2x80x99 are not co-axial, and in addition the pocket containing the coil springs is not formed from one piece of material.
Because the coil springs in the xe2x80x98spring unitsxe2x80x99 disclosed in U.S. Pat. No. 3,462,779 are in side-by-side relationship within the xe2x80x98spring unitxe2x80x99, they are considered to be unsuitable for use in the construction of a bed, divan bed, or mattress, since the xe2x80x98spring unitsxe2x80x99 would not function in the desired way.
Also, as the second spring in publication No WO 98/25503 is freely movable within the first spring, it is not possible to control the movement of the second spring within the first spring.
The present invention seeks to provide an improved form of spring unit which will obviate the disadvantages of known spring units.
According to the present invention there is provided a spring unit comprising a pocket of fabric or other suitable material and having at least two sub-pockets, each of said sub-pockets containing a resilient member, said pocket being formed from a single piece of fabric or other suitable material and said resilient members being mutually co-axial.
Said pocket will preferably be divided across laterally, or diagonally. Said resilient members will preferably be springs, and said sub-pockets may be of equal length or of differing lengths.
Said pocket will preferably be divided by fabric or other suitable material which is integral with the fabric or other suitable material of said pocket. Alternatively, said pocket may be divided by discrete piece(s) of fabric or other material which is secured to said pocket so as to form said sub-pockets.
Said springs, at least when housed or contained in said sub-pockets, and/or prior to being housed or contained in said sub-pockets, will be of equal or unequal lengths, and said springs will have equal or differing rates of compression.